Matsuoka was born as the fourth son to a shipping magnate in Kumage District, Yamaguchi Prefecture (now part of the city of Hikari). At the age of 11, his father’s business went bankrupt, and Matsuoka was sent to the United States with a cousin in 1893 under the sponsorship of Methodist missionaries to study English. He settled in Portland, Oregon, living initially at the Methodist Mission, and was subsequently taken into the household of the widower William Dunbar, which included Dunbar's son Lambert, and Dunbar's sister, Mrs. Isabelle Dunbar Beveridge. Mrs. Beveridge served as a foster mother to Matsuoka and helped him adjust to American society. Matsuoka's affection for her lasted well after he returned to Japan. She died in 1906.[1][2]

While living at Mrs. Beveridge, Matsuoka became a PresbyterianChristian, being baptized by a Rev. Kawabe.[3][4] His biographer Lu comments however that "Still, the requirement of unquestioned submission to one God remained alien to him. Religion to him was a mere cultural milieu. While in America, he was happy to be a Christian and become part of its culture. Back in Japan, he was equally conformable playing homage to the Buddha statues in a Shin temple in Murozumi, much to the delight of his mother. As a foreign minister he was remembered for his obsessive desire to worship at Ise and other Shinto shrines. Viewing religion as he did, Matsuoka found no contradiction in these actions."[3]

Matsuoka enrolled at Portland's Atkinson Grammar School (which still exists as Atkinson Elementary School), and due to the influence of the Dunbar family, converted to Christianity[5] taking the name of “Frank Matsuoka”. He later moved to Oakland, California, with his older brother Kensuke and attended Oakland High School for 18 months. He then returned to Portland and studied law, paying his way by various odd jobs, including busboy, door-to-door salesman (of coffee) and interpreter for a Japanese contractor.[6]

On Matsuoka’s return to Japan in 1902, he attempted to gain admission to Tokyo Imperial University, but was unsuccessful due to his lack of connections and the lack of acceptance of his studies overseas by the Tokyo University Law School. In 1904, Matsuoka decided to pursue a career as a bureaucrat instead, and passed the Foreign Service examinations and was accepted into the Foreign Ministry. Within two years, he was appointed vice-consul at the Japanese consulate in Shanghai. He was subsequently attached to the Governor-General of the Kwantung Leased Territory, where he became acquainted with Gotō Shinpei, then president of the South Manchuria Railway and Yamamoto Jōtarō, then working for Mitsui in developing the natural resources of Manchuria. Over the next 18 years Matsuoka advanced quickly through the ranks of diplomats. He was briefly assigned as First Secretary of the Japanese Embassy in Washington D.C. in 1914, and was a member of the Japanese delegation to the Paris Peace Conference in 1919. Matsuoka served as secretary to Prime MinisterTerauchi and to Terauchi’s Foreign Minister Gotō Shinpei, where his knowledge of the English language was an asset. Matsuoka was also an outspoken defender of Japanese participation in the Siberian Intervention against the Bolshevik forces in the Russian Civil War.

Matsuoka was assigned as Japanese Consul to China in 1921, but turned down the assignment to return to Manchuria as a director of the South Manchurian Railway Company in 1922. In 1927, Matsuoka was promoted to the position of Vice-President of the South Manchurian Railway Company.[7] He was also responsible for the expansion of the coal mines in Fushun and the construction of a coal liquefaction plant. However, in 1930, he resigned from the South Manchurian Railway and returned to Japan. In the 1930 General Election, Matsuoka ran for a seat in the Lower House of the Diet of Japan from Yamaguchi Prefecture with the support of the Rikken Seiyūkai (Constitutional Association of Political Friendship) political party.

However, following the Manchurian Incident of 1931, the establishment of Manchukuo and the Lytton Report to the League of Nations condemning Japan’s actions, Matsuoka was drawn back into the arena of foreign affairs to head Japan’s delegation to the League of Nations in 1933. Matsuoka gained international notoriety for a speech condemning the League of Nations and announcing Japan’s withdrawal, leading the Japanese delegation out of the League's assembly hall.[8][9]

Following his return to Japan, Matsuoka announced his resignation from the Rikken Seiyūkai and his intent to form his own political party modeled after the National Fascist Party in Italy. However, the party never gained the mass support Matsuoka had anticipated, and in 1935 he returned to Manchuria as president of the South Manchuria Railway. He held that post to 1939.[7] Despite his admiration of the Italian fascist movement, Matsuoka was also a supporter of the plan to settle Jewish refugees in Manchukuo.

On December 31, 1940, Matsuoka told a group of Jewish businessmen that he was "the man responsible for the alliance with Adolf Hitler, but nowhere have I promised that we would carry out his anti-Semitic policies in Japan. This is not simply my personal opinion, it is the opinion of Japan, and I have no compunction about announcing it to the world."[10]

During March–April 1941 Matsuoka visited Moscow and Berlin. On March 29, 1941, at a conversation with German Minister of Foreign Affairs Joachim von Ribbentrop, Ribbentrop was instructed to not tell the Japanese anything about the upcoming Operation Barbarossa, and that the Japanese be kept in the dark about Germany's plans.[11] Ribbentrop tried to convince Matsuoka to urge the government in Tokyo to attack Singapore, claiming the British navy was too weak to retaliate due to its involvement in the Battle of the Atlantic. Matsuoka responded to this by stating preparations to occupy Singapore were under way.[12]

Matsuoka also signed the Soviet–Japanese Neutrality Pact during his visit to Moscow in April 1941. However, after Nazi Germany's invasion of the Soviet Union in June 1941, Hitler proposed to Matsuoka that Japan take part in the attack as well. Matsuoka became a fervent supporter of the idea of a Japanese attack on Siberia, and constantly pressured Konoe and the leaders of the Imperial Japanese Army and Imperial Japanese Navy to mobilize the military for that purpose. In the end, both the army and the navy as well as Konoe decided to concentrate military efforts on targets south of Japan.

Despite the military's opposition to his ideas, Matsuoka continued to loudly advocate an invasion of Russia and became increasingly reckless in his diplomatic dealings with the United States, which he believed was conspiring to provoke Japan into a war. Matsuoka's hostility towards the United States (a vocal opponent of Japan's military campaigns) alarmed Konoe, who wanted to avoid war with the United States. Konoe and the military hierarchy colluded to get rid of Matsuoka. To this end, Konoe resigned in July 1941 and his cabinet ministers resigned with him, including Matsuoka. Konoe immediately was made prime minister again, and replaced Matsuoka as Foreign Minister with Admiral Teijirō Toyoda.

When the Pacific war broke out, Matsuoka professed, "Entering into the Tripartite Pact was the mistake of my life. Even now I still keenly feel it. Even my death won't take away this feeling."[13] Matsuoka subsequently drifted into obscurity and lived in retirement through the war years.

^"Matsuoka Honors Woman Kind to Him," Nevada State Journal, April 10, 1933, p2. - "In 1933, after Japan's withdrawal from the League of Nations in Geneva, Matsuoka stopped in Portland on his way back to Japan, and placed a marker at Mrs. Beveridge's gravesite, with an inscription that read, "Raised by the loving hands of Yosuke Matsuoka, in token of the lasting gratitude for the sympathy and gentle kindness of a woman who, next to his mother, shaped his mind and character."

^David Jon Lu, Agony of Choice: Matsuoka Yosuke and the Rise and Fall of the Japanese Empire, 1880-1946 (Lexington Books, 2002), pp. 6-7